MSCHF tried making a Steam page. It got banned on the same day the game went live.
As for the motive of Steam's ban, anime-themed visual novels can be quite hotsy-totsy with this one not being too lewd. Steam tends to disproportionately target small and independent developers with banishments while major videogame studios get away with quite a lot (mulling over that, this is similar to how Spotify treats musicians, actually).